net: dsa: felix: convert to the new .change_tag_protocol DSA API

In expectation of the new tag_ocelot_8021q tagger implementation, we
need to be able to do runtime switchover between one tagger and another.
So we must structure the existing code for the current NPI-based tagger
in a certain way.

We move the felix_npi_port_init function in expectation of the future
driver configuration necessary for tag_ocelot_8021q: we would like to
not have the NPI-related bits interspersed with the tag_8021q bits.

The conversion from this:

	ocelot_write_rix(ocelot,
			 ANA_PGID_PGID_PGID(GENMASK(ocelot->num_phys_ports, 0)),
			 ANA_PGID_PGID, PGID_UC);

to this:

	cpu_flood = ANA_PGID_PGID_PGID(BIT(ocelot->num_phys_ports));
	ocelot_rmw_rix(ocelot, cpu_flood, cpu_flood, ANA_PGID_PGID, PGID_UC);

is perhaps non-trivial, but is nonetheless non-functional. The PGID_UC
(replicator for unknown unicast) is already configured out of hardware
reset to flood to all ports except ocelot->num_phys_ports (the CPU port
module). All we change is that we use a read-modify-write to only add
the CPU port module to the unknown unicast replicator, as opposed to
doing a full write to the register.
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/dsa/ocelot/felix.c

 // SPDX-License-Identifier: GPL-2.0
-/* Copyright 2019 NXP Semiconductors
+/* Copyright 2019-2021 NXP Semiconductors
  *
  * This is an umbrella module for all network switches that are
  * register-compatible with Ocelot and that perform I/O to their host CPU
@@ -24,11 +24,140 @@
 #include <net/dsa.h>
 #include "felix.h"
 
+/* The CPU port module is connected to the Node Processor Interface (NPI). This
+ * is the mode through which frames can be injected from and extracted to an
+ * external CPU, over Ethernet. In NXP SoCs, the "external CPU" is the ARM CPU
+ * running Linux, and this forms a DSA setup together with the enetc or fman
+ * DSA master.
+ */
+static void felix_npi_port_init(struct ocelot *ocelot, int port)
+{
+	ocelot->npi = port;
+
+	ocelot_write(ocelot, QSYS_EXT_CPU_CFG_EXT_CPUQ_MSK_M |
+		     QSYS_EXT_CPU_CFG_EXT_CPU_PORT(port),
+		     QSYS_EXT_CPU_CFG);
+
+	/* NPI port Injection/Extraction configuration */
+	ocelot_fields_write(ocelot, port, SYS_PORT_MODE_INCL_XTR_HDR,
+			    ocelot->npi_xtr_prefix);
+	ocelot_fields_write(ocelot, port, SYS_PORT_MODE_INCL_INJ_HDR,
+			    ocelot->npi_inj_prefix);
+
+	/* Disable transmission of pause frames */
+	ocelot_fields_write(ocelot, port, SYS_PAUSE_CFG_PAUSE_ENA, 0);
+}
+
+static void felix_npi_port_deinit(struct ocelot *ocelot, int port)
+{
+	/* Restore hardware defaults */
+	int unused_port = ocelot->num_phys_ports + 2;
+
+	ocelot->npi = -1;
+
+	ocelot_write(ocelot, QSYS_EXT_CPU_CFG_EXT_CPU_PORT(unused_port),
+		     QSYS_EXT_CPU_CFG);
+
+	ocelot_fields_write(ocelot, port, SYS_PORT_MODE_INCL_XTR_HDR,
+			    OCELOT_TAG_PREFIX_DISABLED);
+	ocelot_fields_write(ocelot, port, SYS_PORT_MODE_INCL_INJ_HDR,
+			    OCELOT_TAG_PREFIX_DISABLED);
+
+	/* Enable transmission of pause frames */
+	ocelot_fields_write(ocelot, port, SYS_PAUSE_CFG_PAUSE_ENA, 1);
+}
+
+static int felix_setup_tag_npi(struct dsa_switch *ds, int cpu)
+{
+	struct ocelot *ocelot = ds->priv;
+	unsigned long cpu_flood;
+
+	felix_npi_port_init(ocelot, cpu);
+
+	/* Include the CPU port module (and indirectly, the NPI port)
+	 * in the forwarding mask for unknown unicast - the hardware
+	 * default value for ANA_FLOODING_FLD_UNICAST excludes
+	 * BIT(ocelot->num_phys_ports), and so does ocelot_init,
+	 * since Ocelot relies on whitelisting MAC addresses towards
+	 * PGID_CPU.
+	 * We do this because DSA does not yet perform RX filtering,
+	 * and the NPI port does not perform source address learning,
+	 * so traffic sent to Linux is effectively unknown from the
+	 * switch's perspective.
+	 */
+	cpu_flood = ANA_PGID_PGID_PGID(BIT(ocelot->num_phys_ports));
+	ocelot_rmw_rix(ocelot, cpu_flood, cpu_flood, ANA_PGID_PGID, PGID_UC);
+
+	return 0;
+}
+
+static void felix_teardown_tag_npi(struct dsa_switch *ds, int cpu)
+{
+	struct ocelot *ocelot = ds->priv;
+
+	felix_npi_port_deinit(ocelot, cpu);
+}
+
+static int felix_set_tag_protocol(struct dsa_switch *ds, int cpu,
+				  enum dsa_tag_protocol proto)
+{
+	int err;
+
+	switch (proto) {
+	case DSA_TAG_PROTO_OCELOT:
+		err = felix_setup_tag_npi(ds, cpu);
+		break;
+	default:
+		err = -EPROTONOSUPPORT;
+	}
+
+	return err;
+}
+
+static void felix_del_tag_protocol(struct dsa_switch *ds, int cpu,
+				   enum dsa_tag_protocol proto)
+{
+	switch (proto) {
+	case DSA_TAG_PROTO_OCELOT:
+		felix_teardown_tag_npi(ds, cpu);
+		break;
+	default:
+		break;
+	}
+}
+
+static int felix_change_tag_protocol(struct dsa_switch *ds, int cpu,
+				     enum dsa_tag_protocol proto)
+{
+	struct ocelot *ocelot = ds->priv;
+	struct felix *felix = ocelot_to_felix(ocelot);
+	enum dsa_tag_protocol old_proto = felix->tag_proto;
+	int err;
+
+	if (proto != DSA_TAG_PROTO_OCELOT)
+		return -EPROTONOSUPPORT;
+
+	felix_del_tag_protocol(ds, cpu, old_proto);
+
+	err = felix_set_tag_protocol(ds, cpu, proto);
+	if (err) {
+		felix_set_tag_protocol(ds, cpu, old_proto);
+		return err;
+	}
+
+	felix->tag_proto = proto;
+
+	return 0;
+}
+
 static enum dsa_tag_protocol felix_get_tag_protocol(struct dsa_switch *ds,
 						    int port,
 						    enum dsa_tag_protocol mp)
 {
-	return DSA_TAG_PROTO_OCELOT;
+	struct ocelot *ocelot = ds->priv;
+	struct felix *felix = ocelot_to_felix(ocelot);
+
+	return felix->tag_proto;
 }
 
 static int felix_set_ageing_time(struct dsa_switch *ds,
@@ -527,28 +656,6 @@ static int felix_init_structs(struct felix *felix, int num_phys_ports)
 	return 0;
 }
 
-/* The CPU port module is connected to the Node Processor Interface (NPI). This
- * is the mode through which frames can be injected from and extracted to an
- * external CPU, over Ethernet.
- */
-static void felix_npi_port_init(struct ocelot *ocelot, int port)
-{
-	ocelot->npi = port;
-
-	ocelot_write(ocelot, QSYS_EXT_CPU_CFG_EXT_CPUQ_MSK_M |
-		     QSYS_EXT_CPU_CFG_EXT_CPU_PORT(port),
-		     QSYS_EXT_CPU_CFG);
-
-	/* NPI port Injection/Extraction configuration */
-	ocelot_fields_write(ocelot, port, SYS_PORT_MODE_INCL_XTR_HDR,
-			    ocelot->npi_xtr_prefix);
-	ocelot_fields_write(ocelot, port, SYS_PORT_MODE_INCL_INJ_HDR,
-			    ocelot->npi_inj_prefix);
-
-	/* Disable transmission of pause frames */
-	ocelot_fields_write(ocelot, port, SYS_PAUSE_CFG_PAUSE_ENA, 0);
-}
-
 /* Hardware initialization done here so that we can allocate structures with
  * devm without fear of dsa_register_switch returning -EPROBE_DEFER and causing
  * us to allocate structures twice (leak memory) and map PCI memory twice
@@ -578,10 +685,10 @@ static int felix_setup(struct dsa_switch *ds)
 	}
 
 	for (port = 0; port < ds->num_ports; port++) {
-		ocelot_init_port(ocelot, port);
+		if (dsa_is_unused_port(ds, port))
+			continue;
 
-		if (dsa_is_cpu_port(ds, port))
-			felix_npi_port_init(ocelot, port);
+		ocelot_init_port(ocelot, port);
 
 		/* Set the default QoS Classification based on PCP and DEI
 		 * bits of vlan tag.
@@ -593,14 +700,15 @@ static int felix_setup(struct dsa_switch *ds)
 	if (err)
 		return err;
 
-	/* Include the CPU port module in the forwarding mask for unknown
-	 * unicast - the hardware default value for ANA_FLOODING_FLD_UNICAST
-	 * excludes BIT(ocelot->num_phys_ports), and so does ocelot_init, since
-	 * Ocelot relies on whitelisting MAC addresses towards PGID_CPU.
+	for (port = 0; port < ds->num_ports; port++) {
+		if (!dsa_is_cpu_port(ds, port))
+			continue;
+
+		/* The initial tag protocol is NPI which always returns 0, so
+		 * there's no real point in checking for errors.
 		 */
-	ocelot_write_rix(ocelot,
-			 ANA_PGID_PGID_PGID(GENMASK(ocelot->num_phys_ports, 0)),
-			 ANA_PGID_PGID, PGID_UC);
+		felix_set_tag_protocol(ds, port, felix->tag_proto);
+	}
 
 	ds->mtu_enforcement_ingress = true;
 	ds->assisted_learning_on_cpu_port = true;
@@ -614,6 +722,13 @@ static void felix_teardown(struct dsa_switch *ds)
 	struct felix *felix = ocelot_to_felix(ocelot);
 	int port;
 
+	for (port = 0; port < ds->num_ports; port++) {
+		if (!dsa_is_cpu_port(ds, port))
+			continue;
+
+		felix_del_tag_protocol(ds, port, felix->tag_proto);
+	}
+
 	ocelot_devlink_sb_unregister(ocelot);
 	ocelot_deinit_timestamp(ocelot);
 	ocelot_deinit(ocelot);
@@ -860,6 +975,7 @@ static int felix_sb_occ_tc_port_bind_get(struct dsa_switch *ds, int port,
 
 const struct dsa_switch_ops felix_switch_ops = {
 	.get_tag_protocol		= felix_get_tag_protocol,
+	.change_tag_protocol		= felix_change_tag_protocol,
 	.setup				= felix_setup,
 	.teardown			= felix_teardown,
 	.set_ageing_time		= felix_set_ageing_time,

drivers/net/dsa/ocelot/felix.h

@@ -48,6 +48,7 @@ struct felix {
 	struct lynx_pcs			**pcs;
 	resource_size_t			switch_base;
 	resource_size_t			imdio_base;
+	enum dsa_tag_protocol		tag_proto;
 };
 
 struct net_device *felix_port_to_netdev(struct ocelot *ocelot, int port);

drivers/net/dsa/ocelot/felix_vsc9959.c

@@ -1467,6 +1467,7 @@ static int felix_pci_probe(struct pci_dev *pdev,
 	ds->ops = &felix_switch_ops;
 	ds->priv = ocelot;
 	felix->ds = ds;
+	felix->tag_proto = DSA_TAG_PROTO_OCELOT;
 
 	err = dsa_register_switch(ds);
 	if (err) {

drivers/net/dsa/ocelot/seville_vsc9953.c

@@ -1246,6 +1246,7 @@ static int seville_probe(struct platform_device *pdev)
 	ds->ops = &felix_switch_ops;
 	ds->priv = ocelot;
 	felix->ds = ds;
+	felix->tag_proto = DSA_TAG_PROTO_OCELOT;
 
 	err = dsa_register_switch(ds);
 	if (err) {